Pneumatic fastener and like driving machine



June 14, 1966 E. D. NELSON ETAL PNEUMATIC FASTENER AND LIKE DRIVING MACHINE Filed Jan. 29, 1964 3 Sheets-Sheet 1 1 I N A Q KE a 63 4 3 72 ma 3 I .QH w 0 6 a P M 6\ w 6 a 4 2 6 2% 2 INVENTORS EDWARD DONALD NELSON WILL/AM R. BEG/(MAN June 1965 E. D. NELSON ETAL 3,255,674

PNEUMATIC FASTENER AND LIKE DRIVING MACHINE (5 Sheets-Sheet 2 rned Jan. 29, 1964 (x) Q INVENTORS.

\ EDWARD DONALD NELSON WILL/AM R. BECKMA/V June 14, 1966 E. D. NELSON ETAL 3,255,674

PNEUMATIC FASTENER AND LIKE DRIVING MACHINE Filed Jan. 29, 1964 3 Sheets-Sheet 5 [UT mm 228 I I I A 2/7 237 23/ I ||Hl 7' 2/5 I p I I ll I"? 2/8 ZZE/ 1 I l 4 522-%\ yaw 328/ 327 329 539 34 524 i 35 325' 35 /552/ I i i l llm 3/5 W ll 5/2 IIENTORS 3/8 4 EDWARD DONALD NELsb/v I WL/AM R. BECKMA /v United States Patent PNEUMATIC FASTENER AND LIKE DRIVING MACHINE Edward Donald Nelson, Glenview, Ill., and William R.

The present invention relates to improvements in pneumatic fastener and like driving machines, and more particularly concerns a pneumatic'motor device for such machines.

In that class of pneumatic fastener driving tools utilizing the explosion type of pneumatic motor, two problems that have demanded solution are reduction in over-all height of the driving head and speedier return of the driving piston to starting position. In tools of this type, extremely rapid firing has been attained by the literal dumping of pneumatic fluid under continuous pressure into the starting or top end of the cylinder in which the driving piston is reciprocably disposed. Such dumping of the hydraulic fluid, generally compressed air, is accomplished by opening the end of the cylinder which is exposed to the reservoir of air under continuous pressure by moving a control valve from its seat adjacent such end of the cylinder. The mounting of, and control means for, the control valve have gnerally been considered to require a considerable space above the end of the driving piston cylinder, affording an unduly high head on the machine. In addition, often more than desirable complexities have been deemed necessary to effect control of the cylinder controlling valve.

. Return of the driving piston from the end of a driving stroke to starting position has heretofore been accomplished in this type of machine by means of return springs which have been generally found to be undesirable due to high liability to breakage due to the unusually high acceleration in driving of the piston in these machines. To overcome the return spring problem, a pneumatic return arrangement has been adapted by which the pneumatic pressure fluid, such as compressed air under line or'reservoir pressure is impressed on the underside of the piston to drive it to the starting position after a driving stroke. In addition, means have been provided for exhausting the hydraulic fluid trapped between the piston and the cylinder control valve. "While such arrangement does afford desirable piston return, still faster return has been sought.

Accordingly, it is an important object of the present invention to improve fastener and like driving machines by the provision of novel pneumatic motor means which will afford not only simplifications in construction and over-all height, but also will improve the speed of op eration of the machine, more particularly in the return of the piston to starting position from the end of a driving stroke.

Another object of the invention is to provide in fastener or like driving machines improved pneumatic motor structure having novel driving piston return and exhaust means.

A further object of the invention is to provide a novel suction return for the driving pistons in pneumatic fastener and like driving machines.

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Still another object of the invention is 'to provide an improved mounting of the control valve member for explosion type fastener and like driving machine pneumatic motors.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompany drawings, in which:

FIGURE 1 is a fragmentary vertical sectional elevational detail view of a fastener driving machine embodying features of the invention;

FIGURE 2 is a fragmentary vertical sectional detail view of the upper portion of the driving head of the pneumatic motor portion of the structure disclosed in FIGURE 1 and taken in substantially the same plane;

FIGURE 3 is a vertical sectional detail view through a modified construction of the cylinder control valve assembly;

FIGURE 4 is a vertical sectional detail view of another modification;

FIGURE 5 is a vertical sectional detail view of still another modification; and

FIGURE 6 is a vertical sectional detail view of a still further modification. i

A manually operable, portable, pneumatically actuated fastener driving machine 10 exemplary of a practical application of the invention and adapted to drive staple, nail, brad or pin types of fasteners comprises a frontto-rear handle portion 11 joined at its front end to a vertical driving head 12. At its lower end the head portion 12 is joined to the forward end portion of a magazine section 13. Under the driving head 12 and .on the forward end of the magazine section 13 is a driving nose structure 15 provided with a vertical driveway 17 into which fasteners are fed under the thrust of a suitable pusher 18 in the magazine section 13. For driving the fasteners successively longitudinally .out of the fastener driveway 17 through the tip of the nose 15 a fastener driver in the form of a blade 19 extends downwardly into the driveway 17 from a piston 20 which is axially, vertically reciprocable within a cylinder chamber 21 of a cylinder 22 of a pneumatic motor housed within the head section 12. One end of the cylinder 20, namely its upper end is exposed to a reservoir chamber 23 in the head portion or section 12, preferably supplemented by reservoir chamber area 23a of substantial volume within the hollow of handle 11 and connected to a source of pneumatic pressure fluid undersubstantially constant pressure head during operation of the machine. a I

Operation of the driving piston 20 in both driving and return strokes is effected by means of the pneumatic pressure fluid such as compressed air from the reservoir 23. According to the present invention, this is accomplished -by means including a piston type diaphragm control valve member 24 which controls opening and closing of the reservoir-exposed end of the cylinder 22, and means comprising a device 25 associated with the valve member 24 for effecting suction in the cylinder 2-2 between the piston 20 and the valve member 24 in its cylinder closing position for drawing the piston into its ready position adjacent the top end of .the cylinder 22 from its driven position remote from said ready position. I

In the form of FIGURES 1 and 2, the control valve member 24 is of a diameter to fit in free sliding guided relation Within a cylindrical upwardly extending internal cylindrical guide portion 27 integral with the housing casing defining the head section 12 and of a diameter greater than the outside diameter defining the upper end of the cylinder 22, whereby a substantial lower annular marginal portion of the valve member 24 is exposed continuously to the pressure of the pneumatic fluid in the reservoir 23, inclusive of the cylinder-closing position of the valve member. In such closing position of the valve member, a smaller diameter coaxial portion thereof projecting below the pressure-exposed lower margin and providing, in effect, a boss 28 extends downwardly within the upper extremity of the cylinder chamber 21 and provides in its perimeter a radially outwardly opening retaining groove 29 for a fluid sealing gasket ring 30 which seats sealingly against the valve seat provided therefor by the upper extremity of the cylinder 22 for sealing the cylinder against ingress of pneumatic pressure fluid from the reservoir 23 in the cylinder-closing position of the valve member 24.

Normally, while the machine is pressurized, that is pneumatic pressure fluid fills the reservoir areas 23, 23a, the control valve member 24 is pneumatically overbalanced into its cylinder-closing position. To this end, the upper portion of the valve member 24 extends into an inverted cup-shaped closure cap 31 suitably secured on the upper open end of the head section 12. Within the cap 31 is provided a chamber 32 over the crown of the valve member 24. With this chamber communicates a passage 33 formed in the cap and in the adjacent portion of the head section 12 contiguous the handle 11. A rearward branch 34 of the passage communicates with an upwardly opening bore 35 within which is mounted a head portion 37 of a valve body bushing 38. A lower annular groove 39 in the head portion 37 has a plurality of ports 40 communicating with a downwardly opening blind end bore 41 in the bushing with which ports 42 effect communication with an upper sealingly spaced peripheral groove 43 with which communicates a port 44 opening into the reservoir area for thereby delivering pneumatic pressure fluid to and through the passage 33 into valve member biasing relation Within the chamber 32.

When it is desired to actuate the pneumatic motor for driving a fastener, the supply of pneumatic fluid to the passage 33 is disconnected and the chamber 32 bled or exhausted to atmosphere. This is accomplished by suitable means herein comprising a valve member 45 normally biased by means such as a spring 47 and pneumatic pressure fluid thrusting against its head to clear the. ports 40. Upward movement of the valve 45 is adapted to be effected by means such as a trigger lever 48 mounted to be engaged by a lower end terminal 49 on the valve member. When the trigger 48 is swung upwardly, it displaces the valve 45 upwardly to move the head end portion thereof above the ports 40, thus blocking them from the pneumatic fluid supply and opening a by-pass pas-sage through the lower portion of the bushing 38 and through a port 50 into a pasage 51 to bleed otf to atmosphere. In this instance, such bleed off is past a valve 52 shown as held by interlock means 53 in a non-operating or disabled condition affording an open passageway from the passage 51 and past the open valve 52 to an exhaust port 54. Where desired, the valve 52 may be connected to safety trip trigger mechanism, pursuant to the disclosure in Patent 3,172,124 dated March 9, 1965, for controlling the bleed off passage. Instantaneously upon opening of the bleed oif passageway, a pneumatically unbalanced relationship occurs wherein the valve member 24 responds as a poppet to pneumatic pressure on its lower margin to snap upwardly and open a substantial gap over the top of the cylinder 22 whereby pneumatic fluid dumps into the cylinder and drives the piston 20 with high acceleration.

Instantaneously upon release of the control valve 45, resumption of pneumatic loading of the crown of the poppet valve member 24 causes it to resume its drive cylinder-closing position. At this time, however, the drive piston 20 is in its driven position in the lower portion of the cylinder chamber 21 at the end of its driving stroke and must be returned to its starting position. Further, the pneumatic fluid trapped between the piston 20 and the control valve member 24 must be exhausted to enable return of the drive piston. For this purpose, means, including the downwardly directed suction device 25,-func tion in a simple, highly efficient manner, as follows.

Exhaust of the trapped pneumatic fluid between the piston 20 and the control valve member 24 to atmosphere is effected by way of a passageway system through the valve member including a suitable annular series of vertical eccentrically disposed blind end bores 55 (only one of which is shown) opening through the lower face of the valve member 24. Adjacent to their upper blind ends the bores 55 intersect and open into a preferably axially disposed larger diameter blind end bore 57 which opens upwardly through the valve member 24 and into which the member 25 projects slidably as a generally tubular stem extending downwardly from and secured fixedly to the cap member 31 as by means of a screw 58. From the bore 57 an annular series of spaced ports 59 convey the exhausting fluid through the wall of the tubular member 25 into the upper end or throat portion of a downwardly flaring generally conical venturi mouth 60 extendiing down through a reduced diameter lower terminal extension portion 61 of the member 25 and slidably engaged in a complementary reduced diameter lower terminal portion of the blind end bore 57. From the bottom of the reduced diameter portion of the bore 57, a suitable annular series of lateral exhaust passages 62 in the valve member 24 lead to an annular peripheral groove 63 therein to maintain continuous communication with an exhaust port 64 to atmosphere opening through the side wall of the cap 31 in alignment with the groove.

By inducing a suction in the venturi mouth 60, high speed evacuation of the spent pneumatic fluid trapped between the piston and valve members creates a vacuum condition which causes the piston 20 to be snapped upwardly to its starting position by normal atmospheric pressure acting on its underside through the relatively free access of atmospheric pressure into the lower end of the cylinder chamber 21 as through a suitable relief opening 65 into the bottom of the cylinder. Such suction results from directing pneumatic pressure fluid through a venturi orifice 67 immediately upstream fromand causing a pressure drop across the ports 59. Pressure fluid enters the bore of the member 25 above the orifice 67 through a circumferentially spaced set of radial ports 68 extending inwardly from an annular peripheral groove 69 to which leads a diagonal passageway 70 opening at its lower end through. the lower margin of the valve member 24 outwardly adjacent to the sealing ring 30 whereby pressure fluid from the reservoir 23 is adapted to be conveyed to the suction device. It will be observed that suitable longi tudinally spaced sealing rings prevent leakage longitudinally between the member 25 and the Wall defining the bore 57 and maintain pressure separation between the ported sections of the member 25.

In order to avoid unnecessary escape of pressure fluid from the reservoir 23 and to limit expenditure of the pressure fluid to the quite small volume which will create the piston-returning suction, automatic valve means are provided for controlling the pressure fluid delivery passage 70. To this end, a shuttle valve 71 is mounted for reciprocable movement within an eccentric vertical bore 72 intersecting the pressure fluid passage 70. In the normal ready-to-fire condition of the pneumatic motor, the valve 71 closes the passage 70 as shown in FIGURE 1. In this position the valve 71 is held by 21 depending stop stem 73 in closing relation to the lower portion of the passage 70 while the upper or head end of the valve member 71 is exposed to the upper portion of the passage 70. Further, a downwardly extending reduced diameter stem 74 on the valve member 71 engages at its tip against the crown of the piston 20 and maintains it in slightly spaced relation to the bottom face of the valve member 24 to avoid any tendency toward clinging and to assure instantaneous breakaway when the valve member 24 is snapped from its seat to open the cylinder 22 as shown in FIGURE 2.

Upon opening of the valve member 24, pressure fluid entering the cylinder as shown by directional arrows in FIGURE 2 enters the passages 55 and passes by way of the ports 59 and upwardly through the venturi throat 67 and the ports 68 and the groove 69 into the upper portion of the passage 70 and drives the valve 71 downwardly to follow the descending piston 20 until the valve member 71 stops against a shoulder 75 wherein the lower portion of the passage 70 is opened to communication with the bore 72. Pressure relief for the space between the head portion of the valve 71 and a shoulder 75 is afforded by a passage extending from adjacent to the shoulder to the control chamber 32. At this same time, the tip of the venturi mouth extension 61 of the member 25 seats as a shut-off valve against a resilient rubber-like sealing disk 77 mounted in the bottom of the blind end bore 57 below the inner end of'the exhaust passage 62, thus preventing escape of pressure fluid from the reservoir.

When the control poppet 24 is returned to cylinderclosing position, the shuttle valve 71 remains in its depressed, delivery-passage-clearing position until as a result of the suction created by pressure fluid delivered to and through the member 25, the piston 20 is snapped to its upper, ready position, and drives upwardly on the valve stem 74 to shift the shuttle valve 71 into deliverypassage-closing position, where it is held by pressure fluid through the passage 76. Thus, the piston 20 shuts off the piston-returning suction automatically and only as the piston reaches its ready position. Dropping of the piston 20, which is preferably made from a lightweight material such as aluminum, is substantially precluded by the moderate friction of a sealing ring 78 carried in its perimeter in engagement with the cylinder wall surface defining the cylinder chamber 21.

Although excellent guiding of the valve member 24 is accomplished in the cylindrical guide portion 27 of the head section 12, a stabilizing, anti-cocking guide is afforded adjacent to the crown of the valve member by sliding engagement with the wall of the cap member 31. By preference, the diameter of the chamber-defining inner wall surface of the cap member is slightly larger than the guide bore cylinder diameter 27 and the valve member 24 is provided with an annular peripheral flange 79 of complementary diameter carrying a sealing ring 80 sealing against leakage of pressure fluid from the chamber 32 into the intermediate annular exhaust groove 63. A sealing ring 81 in the perimeter of the valve member 24 engages the guide surface 27 and prevents leakage of pressure fluid from the reservoir past the valve member into the exhaust groove 63. This arrangement avoids the need of a gasket between the confronting edges at the parting between the upper end of the head section 12 and the edge of the closure cap 31 where such parting is located to remain between the sealing rings 80 and 81 in all positions of the valve member 24.

In addition to the greater diameter of the crown portion of the valve member 24 which affords overbalancing pressure on the crown from the pressure fluid delivered through the passageway 33, a substantial biasing force on the valve member toward closing position is exerted by the downward thrust of the pressure fluid stream from the venturi mouth 60 toward the base afforded by the valve member 77. Therefore, a starting biasing spring is unnecessary to assure rapid, positive cylinder-closing movement of the control valve member 24 when the de- 6 livery passage 33 is opened to the reservoir area following actuation of the pneumatic motor for driving the piston in a fastener driving stroke.

In the form of FIGURE 3, a machine 10 is provided with a pneumatic motor functioning substantially the same as the pneumatic motor in the machine 10 of FIG- URES 1 and 2, but equipped with a modified driving cylinder control valve and piston returning suction arrangement. In this form, a piston type reciprocable diaphragm control valve member 82 is provided which carries a laterally, herein horizontally, extending venturi type suction inducing member 83 in unitary assembly therewith.

The valve member 82 is reciprocably guided by a cylindrical upward extension 27' of the head section 12' for movement between cylinder-closing and cylinderopening positions. On its upper end portion the valve member 82 has a slightly larger diameter head flange 84 slidably engaged within the cylindrical wall surface of larger diameter than the guide surface 27' and located within the chamber 32 of the cap 31'. Thereby a positively overbalanced pressure differential between the crown of the valve member 82 and the lower surfaces of i perimeter of a lower central boss portion 88 of the valve member 82 effects a pressure seal between the valve member and the cylinder in the closed posit-ion of the valve member.

In the self-contained arrangement of the control valve member 82 and the suction device 83, the latter is in the form of a tubular bushing which is threadedly secured in a blind end bore 89 extending transversely within the body of the valve member 82 and opening into an annular peripheral exhaust groove 90 in the valve member communicating in all positions of the valve member with an exhaust port 91 opening through the wall of the cap 31. Extending upwardly in the .valve member 82 to intersect the bore 89 is a cylinder evacuating bore or port 92 with which communicates an annular peripheral groove 93 in the suction member 83 from which extend inwardly ports 94 communicating with the throat of a venturi mouth 95 opening toward the groove 90 and immediately downstream from a venturi orifice 97 communicating at the inner end of the member 83 with a generally axially extending, vertical shuttle valve bore 98 into which leads a'pressure fluid delivery passage 99 extending diagonally from the continuously exposed lower margin of the valve member 82. Within the bore 98 a shuttle valve 100 is adapted to engage at its crown against a depending stop pin 101 in position to block the passage 99 while a depending smaller diameter extension 102 of the valve member extends downwardly and at its tip maintains a break-away gap between the crown of the piston 20' and the bottom face provided by the boss portion 88 of the poppet valve 82.

When the pneumatic motor of the machine 10 is to be operated for driving of the piston 20' in a fastener setting stroke, and pressure is bled from the valve chamber 32', unseating of the poppet valve'82 is accompanied by movement upwardly of a shuttle-type spool valve 103 in a bore 104 which intersects the exhaust end portion of the transverse bore 89 in front of the venturi mouth 95. Presssure fluid enters the lower end of the valve bore 104 through a port 105 in the exposed lower margin of the poppet valve member 82. As a result, when the poppet valve 82 is unseated, the discharge end of the venturi mouth is closed, and pressure fluid entering the venturi member 83 from the passage 92 is diverted through the venturi 97 to act on the shuttle valve 100 to drive it downwardly in the direction of movement of the piston 20' and thus open the pressure delivery passage 99.

In the open position of the valve member 82, an enlarged diameter head 107 on the spool valve 103 is displaced upwardly in an enlargement 108 of the bore 104 opening through the crown of the valve member 82, the head 107 coming to a stop against the opposing roof provided by the cap member 31'.

At the end of a firing or driving stroke of the piston 20, resumption of fluid pressure in the valve chamber 32 not only snaps the poppet valve 82 into cylinderclosing position, but also snaps the spool valve 103 into its non-operating venturi opening position, by reason of the pressure diflerential between the head 107 and the valve portion 103 of the spool valve. As a result, pressure fluid passing through the venturi orifice 97 creates a strong suction through the ports 94 and a vacuum condition in the cylinder 22 between the piston 20' and the closed poppet valve 82 for quick return of the piston 20' to starting position wherein it snaps the shuttle valve 100 into its closing position relative to the pressure delivery passage 99. A passage 98a exhausts the differential smaller lower area of the valve 100 during firing of the machine and provides holding pressure thereagainst in the ready-to-fire condition.

It will be observed that in the form of the device shown in FIGURE 3, no biasing or starting spring is needed for the poppet valve 82 and an eflicient, guided, noncocking relationship is maintained between the smaller diameter lower portion of the poppet valve within the guide cylinder surface 27 and the guiding engagement of the larger diameter crown flange portion 84 with the guide 4 surface of the cap wall. Respective sealing rings 109 and 109a mounted in vertically spaced relation in the perihpe-ry of the poppet valve member 82 prevent leakage to the exhaust groove 90.

Where there is requirement for smaller transverse space adaptation of the pneumatic motor and low silhouette may be sacrificed for such transverse space minimization, the arrangement as depicited in FIGURE 4 may be employed attaining the advantages of fast suction return of the driving piston of the pneumatic motor. To this end, a machine 110, exemplified as a fastener driving machine which, except for details of the pneumatic motor to be described, will be understood to embody similar features as those described in respect to FIGURE 1.

In the machine 110, a driver 111 is attached to and is reciprocably driven in driving and return strokes by a piston 112 carrying a peripheral sealing ring 113 which is slidably engaged with a cylindrical chamber wall 114 of a cylinder 115 having its inner upper end exposed to a reservoir 117 within a head section 118 of the machine which has suitably secured to its upper end a generally inverted cup-shaped closure cap 119 with a sealing gasket 120 in the joint between the head and cap. Opening and closing of the cylinder 115 for respectively driving and return of the piston 112 is effected by means of a poppettype control valve diaphragm piston member 121 provided with an annular radial head flange 122 carrying a peripheral sealing ring 123 engaging the cylindrical inner wall of the cap 119 slidably and separating a valve pressure chamber 124 within the cap from the reservoir 117. Pressure fluid delivered through a passage 125 into the top of the chamber 124 drives the valve member 121 downwardly to effect seating of a sealing ring 127 carried peripherally within a groove 127a in the lower end portion of the valve member 121 onto the seat provided by the upper end of the cylinder 115. In this instance a biasing or starting spring 128 of coiled compression form is disposed between the cap 119 and the control valve memher 121 for supplementing the fluid pressure on top of the flange 122 to overcome the fluid pressure on the under surfaces of the valve member and more particularly the marginal flange 122 for seating the control valve closingly on the driving piston cylinder.

When the piston 112 is to be driven in a driving stroke, pressure from the valve chamber 124 is bled off through the passage whereby the fluid pressure in the reservoir 112 acting on the exposed underside of the marginal flange 122 snaps the valve member 121 upwardly from its seat so that pressure fluid from the reservoir 117 will dump onto the piston 112 and drive it downward in a working stroke. As this occurs, an upwardly projecting guide stem 129 sealingly slidably engaged in a downwardly opening axial blind end bore 130 in the thickened roof wall portion of the cap 119 engages a resilient stationary valve seat 131 in the root of the bore 130 and thus closes off from an exhaust port 132, an exhaust passage through the poppet control valve member 121 leading from its lower cylinder registering end. In this instance, the stem 129 provides a venturi extension projecting upwardly from a suction tube member 133 threadedly secured in a stepped bore 134 axially in the vertically elongated poppet valve member 121.

Withinthe stern 129 is an upwardly opening flaring venturi mouth 135 Within the throat of which lateral ports 137 communicating with a peripheral groove 138 are adapted to receive pneumatic fluid from a suitable plurality of passages 139 opening through the lower face of the valve member 121 overlying the cylinder chamber 114. A free flowing, non-throttling flow area relationship of the passages 139 to the ports 137 is afforded, similarly as the passages 55 to the ports 59 in FIGURE 1 and the passage 92 to the .ports 94 in FIGURE 3.

Upon closing of the exhaust passageway by engagement betwen the top of the stem 129 and the valve seat 131, in shut-01f valve relation, pressure fluid entering by way of the passages 139 and the ports 137 into the venturi mouth 135 passes down through a venturi orifice 140 immediately adjacent to the orifices 137 and forces downwardly a shuttle valve 141 guided in a cylindrical axial bore portion 142. A reduced diameter axial downwardly extending stern 143 of the valve 141 is adapted to project downwardly through the lower end of the valve member 121 to engage at its tip against the crown of the piston 112 and maintain a break-away gap in the uppermost, ready position of the piston. At its upper end, the main body portion of the shuttle valve 141 is adapted to engage a downwardly facing seat 144 and a sealing ring 145 adjacent to such seat and located above the mount of a passage 147 extending laterally through the valve member 121 for conducting pressure fluid to the bore 142.

As the shuttle valve 141 is driven downwardly during driving stroke actuation of the piston 112, the valve 141 comes to rest on an upwardly facing shoulder 148 in position to uncover the passage 147. A pressure relief passage 149 leads from adjacent the shoulder 138 to the top of the valve member 121 whereby bleed off is effected when the valve chamber 124 is bled to atmosphere. Although pressure fluid is introduced by the passage 149 under the shuttle valve member 141 in the valve-closing position of the valve member 121, the substantially smaller underside diameter of the shuttle valve exposed to such pressure fluid as compared to the area of its upper end so exposed maintains the shuttle valve in its down position on the seat 148 until the shuttle valve is physically shifted upwardly against the seat 144 by thrust of the piston 112 against the stem 143 in return of the piston to its starting or ready position.

At the end of a driving stroke of the piston 112, and return of the control valve 121 to cylinder-closing position, pressure fluid is delivered by the passage 147 through the venturi orifice 140 and this eflects a substantial pressure drop and thus suction across the orifices 147, whereby the suction evacuation of pneumatic fluid trapped between the piston 112 and the poppet valve 121 draws the piston 112 up to starting position with a snap action. Such venturi pressure drop suction is enhanced by the provision of an orifice restricting projection 150 rising from the head of the shuttle valve 141. Such projection 7 v '9 substantially increases the velocity and thus pressure drop through the venturi orifice 140.

If in any of the described embodiments the shuttle valve is not automatically returned to upward, closing position by the drive piston a malfunction alarm is evident by prolonged hissing of escaping pressure fluid from the exhaust-venturi suction system.

Advantages inherent in at least certain of the forms of the invention already described herein, especially with respect to low silhouette of the head section of the machine, simplification of mechanism and high efiiciency are attainable in the modification of FIGURE 5, although in this form the suction return feature is not employed. Otherwise, it will be understood that the machine generally identified by the reference numeral 210, functions substantially the same as the machine 10 of FIGURE 1. In this instance, a driver is carried by a driving piston 212 which is reciprocable in driving and return strokes wherein a peripherally carried sealing ring 213 is slidably engaged in a cylinder chamber defined by a wall 214 in a cylinder 215 having its upper inner end exposed to a pneumatic pressure fluid reservoir 217 within a head section 218. A closure cap 219 of inverted generally cup-shape is suitably secured on the upper open end of the head section 218, with a sealing gasket 220 interposed at the joint.

For controlling the reservoir-exposed end of the cylinder 215, a poppet control valve diaphragm piston member 221 is reciprocably vertically movably guided within the cylindrical wall of the cap member 219 and carries in its periphery respective sealing rings 222 and 223 affording stable, non-cocking guided support for the valve member. For normally driving the control poppet valve 221 into cylinder-closing position, pressure fluid is introduced over the crown of the valve member into a valve chamber 224 through a passage 225. In this instance, a suitable coiled compression spring 227 affords supplemental biasing. force to overcome the slightly greater area on the underside of the poppet valve 221 exposed to pressure fluid in the open position of the valve. In the closed position of the poppet valve 221, only a limited annular lower marginal area is exposed to the pressure fluid in the reservoir 217 about a sealing ring 228 which is carried in a groove 229 opening radially in a downwardly projecting central boss portion 230 on the valve member 221 and fitting freely within the mouth of the cylinder 215.

A break-away gap between the crown of the driving piston 212 and the poppet valve boss 230 is maintained by a downwardly projecting tip 231 on a stem 232 projecting axially downwardly from the roof of the cap 219 through a suitable bore 233 in the valve member 221. In addition to its piston stop function, the tip 231 serves to support a closure valve ring 234 which in the open position of the valve 221 engages an upwardly facing valve seat 235 about an exhaust port 237 opening through the 'b0ss230 and through which the stem projects. Adjacent to shut off valve seat 235, one or more exhaust passages 238 lead off laterally to an exhaust groove 239 between the sealing rings 222 and 223 and communicating with an exhaust port 240 through the wall of the cap 219. Through this arrangement, in the cylinder-closing position of the poppet valve 221, an exhaust passage is opened to atmosphere for pneumatic fluid trapped between the piston 212 and the poppet valve 221 at the end' of a piston driving stroke. However, automatically upon opening of the poppet valve 221, the exhaust passage is shut off by the valve 234, 235. In this instance, return of the piston 212 is effected in any preferred manner such as by the Well-known air return arrangement whereby pressure is applied to the underside of the piston 212 for this purpose.

FIGURE 6 depicts another form of the invention similar to FIGURE but embodying a driving machine 310. In this arrangement, a driving member is carried by a piston 312 having a peripheral sealing ring 313 engaging slidably in the wall defining a cylinder chamber 314 in a cylinder 315 having its inner upper end exposed to a pneumatic pressure fluid reservoir 317 in a head section 318 having suitably secured in closing relation to its upper end a generally inverted cup-shaped closure cap 319 defining therein a valve chamber 320 to accommodate a vertically reciprocable poppet valve diaphragm control piston member 321 having a head flange 322 carrying a peripheral sealing ring 323 which engages slidably with the cylindrical wall of the cap member 319. In this instance, the wall of the cap member is of at least slightly larger diameter than cylindrical guide surface 324 guidedly slidably engaged by a sealing ring 325 mounted in a reduced diameter lower portion of the valve member 321 in vertically spaced relation below the sealing ring 323 and with an exhaust groove 327 between the rings communicating with an exhaust port 328 through the wall of the closure cap. In this arrangement, no sealing gasket is needed between'the joining edges of the head section 318 and the cap 319 since pressure fluid leakage is prevented by the sealing rings 323 and 325 which flank the joint. 7

Lateral exhaust passages 329 lead inwardly from the groove 327 to a valve seat 330 about an exhaust port 331 through a downwardly projecting boss 332 on the lower end of the poppet valve 321 received freely within the mouth of the cylinder 315 and carrying in a radially opening groove 333 thereabout a sealing ring 334 which seats sealingly on the valve seat provided 'by the top of the cylinder 315 in the cylinder-closing position of the poppet valve 321. A limited area break-away spacer projection 335 is provided on the crown of the piston 312 to oppose the boss 332.

Normally, pressure fluid delivered from the reservoir area of the machine through a passage 337 pressurizes the crown of the poppet valve 321 and drives it into sealing relation to the end of the cylinder 315. In this position of the poppet valve, the exhaust passage from the area between the piston 312 and the poppet valve is opened to atmosphere.

When the poppet valve 321 is unseated by bleading oil? the valve chamber 320 to atmosphere, so that pressure fluid in the reservoir 317 acting on the exposed lower margin of the poppet valve forces it upwardly away from the top of the cylinder 315, a shut 01f valve 338 attached as by means of a screw 339 to the lower end of a stem 340 projecting from the roof of the cap 319 is engaged by the valve seat 330 so that the exhaust passage is closed. If preferred, the screw 339 may include a downward stud projection 339a to project through the port 331 and provide a stop for the piston 312, similarly as the projection 2310f FIGURE 5.

In the machine 310, no biasing spring is needed for thrusting the poppet valve 321 toward closing position because of the advantageous differential in exposed area between the larger crown of the poppet valve as compared to its underside areas. In this form, similarly as in FIGURE 5, air return of the piston 312 may be employed.

In all forms of the invention, it will be observed that all parts of the pneumatic motors are of relatively simple, rugged and efficient construction. In all forms thereis quite limited frictional drag in operation of the cylindercontrolling poppet valve because of the few points of sealing ring contact between the poppet valve and the guide surfaces. Substantial advantage is attained from the axially spaced two ring contact between the perimeter of the poppet valve and the guide surfaces in preventing any tendency toward cocking of the poppet valve in operation due to possible variables or tolerances. Further, it will be observed that since the poppet valves in all instances are cylindrically symmetrical with respect to associated parts, free rotary self-adjustment of the poppet valve can take place for alleviating possible slight imbalances. In all forms, minimum motor height and thus low silhouette is attained and in certain forms even to a gearter extent than others due to the extremely compact arrangement of the operating mechanism.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. In a pneumatic motor device adapter for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted :for movement between closing and open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member,

and a venturi device relative to which said valve member is movably mounted for effecting suction to evacuate the cylinder between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position and including an exhaust passageway extending through and opening from said valve member.

2. A pneumatic motor as defined in claim 1, including a shut off valve structure to close said passageway in the open position of the valve member and to open said passageway in the closed position of the valve member.

3. In a pneumatic motor device adapted for'powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end, and a valve member aligned with said one end, the combination comprising:

means defining a valve chamber associated with said one end of the cylinder,

a valve member mounted in said valve chamber for movement between closing and open positions relative to said cylinder end,

means for controlling opening and closing movements of said valve member,

means for effecting suction to evacuate the cylinder between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position and including an exhaust passageway extending through and opening from said valve member,

said valve chamber having an exhaust port opening therefrom to atmosphere and with said passageway communicating with said port in at least the closing position of the valve member,

and shut off valve stiucture operative to close said passageway in the open position of the valve member.

4. In a pneumatic motor device adapted for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing and open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member,

means including a passage through said valve member for effecting suction to evacuate the cylinder between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position, said suction means comprising a venturi device carried by the valve member,

and shut off valve means mounted on the valve member movable relative to the venturi device and operative to close said passageway in the open position of the valve member and being automatically actuated to open said passageway in the closed position of the valve member. 5. Ina pneumatic motor device adapted for powering a fastener driver and including means defining a reservoir chamber :to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing and open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member, means for effecting suction to evacuate the cylinder between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position and including an exhaust passageway extending through and opening from said valve member, and means operated by the piston for disabling said suction means when the piston reaches said ready position. 6. In a pneumatic motor device adapted for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing and open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member, means for effecting suction to evacuate the cylinder between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position and includ ing an exhaust passageway extending through and opening from said valve member, and means carried by the valve member functioning automatically to disable said suction means in the ready position of the piston and to activate the suction means in the driven position of the piston. 7. In a pneumatic motor device adapted for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing an open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member, means including a passage through said valve member for effecting suction to evacuate the cylinder between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position, and a shuttle valve carried by the valve member for controlling operation of said suction means and having a portion maintaining the piston in spaced breakaway relation to the valve member in the ready position of the piston. 8. In a pneumatic motor device adapted for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a iston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing and open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member, means including a passage through said valve member for effecting suction to evacuate the cylinder between said pistonand said valve member in its closing position for drawing the piston into said ready position from the driven position,

and a shuttle valve for controlling said suction means having suction disabling and suction activating positions in one of which positions it is controlled by said piston. a

9. In a pneumatic motor device adapted for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing'and open positions relative'to said cylinder end, means for controlling opening and closing movements of said valve member, A

means including a passage through said valve member for effecting suction to evacuate the cylinder between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position,

and a shuttle valve having suction device disabling and activating respective positions into one of which positions it is pneumatically actuated and into the other of which positions it is actuated by the piston.

10. In a pneumatic mot-or device adapted for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing and open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member,

said valve member having a passageway for evacuating to atmosphere the cylinder space between the piston and valve member,

a venturi tube carried by the valve member and affording part of said passageway for creating a piston returning suction and projecting in part from the valve member in the opposite direction from said cylinder,

means coacting with the projecting portion of the venturi tube to provide a shut off valve relationship in the open position of the valve member,

and a shuttle valve aligned with said venturi tube in the valve member and having a portion adapted to project from the piston opposing end of the valve member, 1

said shuttle valve being shifted away from the venturi tube by pneumatic pressure in the open position of the valve member and being shifted into disabling position to the venturi tube by engagement of the projecting portion of the shuttle valve by the piston in the closing position of the valve member.

11. In a pneumatic motor device adapted for powering I a fastener driving machine and including housing means defining a pneumatic fluid reservoir to which is exposed one end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

said housing having a valve chamber aligned with said one end and defined by end and side wall portions with an opening to atmosphere leading from said valve chamber through said side wall portion,

a valve structure in said valve chamber reciprocably guided between said one end and said end wall portion into cylinder closing and cylinder opening positions of a face thereof which opposes said one end,

said valve structure having a periphery opposing said side wall portion with an exhaust passageway lead- .ing from said face through said periphery to communicate with said opening to atmosphere,

and shut off valve means disposed in said passageway and closing the passageway in the open position of the valve structure and opening the passageway in the closing position of the valve structure.

12. A pneumatic motor device as defined in claim 11, in which said shut off valve means comprises in part a valve member projecting from said end wall portion into said valve structure.

13. A pneumatic motor device as defined in claim 12, in which said shut off valve memberhas a passage therethrough comprising part of said passageway and opening toward an opposing surface within the valve structure, and means for delivering pneumatic fluid under pressure into said valve member for driving a stream of pneumatic fluid from the valve member against said opposing surface to thrust the valve structure toward its cylinder closing position.

14. A pneumatic motor device as defined in claim 12 wherein said exhaust passageway includes a port opening through said face in alignment with said valve member and having a valve seat thereabout interiorly of the valve structure engageable by complementary valve means on the valve member in shut off relation in the cylinder opening position of the valve structure.

15. A pneumatic motor device as defined in claim 14 I wherein said valve member has a portion thereof projecting through said aligned opening to engage said piston in its ready position for maintaining a breakway gap between the piston and said face of the valve structure.

16. A pneumatic motor device as defined in claim 11 wherein said side wall portion comprises cylindrical guide surfaces at respectively opposite axial sides of said opening to atmosphere and such guide surface nearest said end wall being of larger diameter, and said valve structure having peripheral portions complementary in diameter to said guide surfaces carrying sealing ring means respectively slidably engaging said cylindrical surfaces whereby the valve structure is guided reciprocably in stable manner.

17. A pneumatic motor device as defined in claim 16 wherein said larger diameter cylindrical guide surface and said end wall portion comprise part of a closure cap secured separably to the remainder of the housing means carrying the remaining of said cylindrical guide surfaces.

18. In a pneumatic motor device adapted for powering a fastener driving machine and including housing means defining a pneumatic fluid reservoir to which is exposed one end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

said housing having a valve chamber aligned with said one end and defined by end and side wall portions with an opening to atmosphere leading from said valve chamber through said side wall portion,

a valve structure in said valve chamber reciprocably guided between said one end and said end wall portion into cylinder closing and cylinder opening positions of a face thereof which opposes said one end,

said valve structure having a periphery opposing said side wall portion with an exhaust passageway leading from said face through said periphery to communicate with said opening to atmosphere,

said valve structure having a crown portion of substantially larger area than said face and opposing said end wall portion, and means for impressing pneumatic pressure fluid on said crown in opposition to pressure fluid in the reservoir acting on said face whereby to bias the valve structure normally into said cylinder closing position and being adapted to bleed off pressure from said crown to permit the pneumatic pressure in the reservoir to move the valve structure to the cylinder opening position.

19. In a pneumatic motor device adapted for powering a fastener driver and including means defining a reservoir chamber to which is exposed an end of a cylinder having therein a piston reciprocable between a ready position adjacent to said one end and a driven position remote from said one end,

a valve member mounted for movement between closing and open positions relative to said cylinder end, means for controlling opening and closing movements of said valve member, I and a venturi device mounted on said valve member for effecting suction to evacuate the cylinder. between said piston and said valve member in its closing position for drawing the piston into said ready position from the driven position and including an exhaust passageway extending through and opening from said valve member.

References Cited by the Examiner UNITED STATES PATENTS Brown 60-60 Rockwell 6060 Saurenman 91--461 Doyle 91-423 

1. IN A PNEUMATIC MOTOR DEVICE ADAPTER FOR POWERING A FASTENER DRIVER AND INCLUDING MEANS DEFINING A RESERVOIR CHAMBER TO WHICH IS EXPOSED AN END OF A CYLINDER HAVING THEREIN A PISTON RECIPROCABLE BETWEEN A READY POSITION ADJACENT TO SAID ONE END AND A DRIVEN POSITION REMOTE FROM SAID ONE END, A VALVE MEMBER MOUNTED FOR MOVEMENT BETWEEN CLOSING AND OPEN POSITIONS RELATIVE TO SAID CYLINDER END, MEANS FOR CONTROLLING OPENING AND CLOSING MOVEMENTS OF SAID VALVE MEMBER, AND A VENTURI DEVICE RELATIVE TO WHICH SAID VALVE MEMBER IS MOVABLY MOUNTED FOR EFFECTING SUCTION TO EVACUATE THE CYLINDER BETWEEN SAID PISTON AND SAID VALVE MEMBER IN ITS CLOSING POSITION FOR DRAWING THE PISTON INTO SAID READY POSITION FROM THE DRIVEN POSITION AND INCLUDING AN EXHAUST PASSAGEWAY EXTENDING THROUGH AND OPENING FROM SAID VALVE MEMBER. 